Dermatitis Herpetiformis Patients Research Articles

Intraepithelial lymphocytes bearing the gamma/delta receptor in the oral and jejunal mucosa in patients with dermatitis herpetiformis.

Lymphocytes bearing T cell receptor (TcR) gamma/delta are increased in the jejunal mucosa of patients with dermatitis herpetiformis (DH) and coeliac disease. In this study, we examined whether increased numbers of gamma/delta TcR positive lymphocytes occur in the oral mucosa of patients with DH. Oral and jejunal mucosal biopsies were taken from 13 newly diagnosed and 13 gluten free diet (GFD)-treated patients with DH. Monoclonal antibodies and avidin-biotin peroxidase method was used for staining, and TcR positive cells were counted from the buccal and jejunal epithelium. Very few gamma/delta TcR positive lymphocytes were seen in the buccal epithelium of untreated or GFD-treated DH patients (median 0.4 and 0.3 cells/mm2), whereas alpha/beta TcR positive lymphocytes were frequent in both groups of DH patients (154 and 250 cells/mm2) and healthy controls (135 cells/mm2). The numbers of gamma/delta TcR positive intraepithelial lymphocytes were significantly increased in the jejunum of both untreated (43 cells/mm) and GFD-treated (27 cells/mm) DH patients compared to control patients (2.2 cells/mm). The present study did not, therefore, disclose any evidence for active recruitment of gamma/delta TcR positive lymphocytes in the oral epithelium, but showed substantial amounts of intraepithelial alpha/beta TcR positive lymphocytes both in DH patients and healthy controls.

Diseases associated with dermatitis herpetiformis

We have studied the occurrence of associated diseases in a cohort of 305 patients with dermatitis herpetiformis (DH) followed up for a mean of 10 years. The results were compared with those from 383 patients with coeliac disease (CD). Twenty-nine (9.5%) patients with DH and 73 (19.1%) with CD had concomitant endocrine or connective tissue disorders. The following associations were found: auto-immune thyroid disease (4.3% of DH patients and 6.0% of CD patients), insulin dependent diabetes (1.0% DH and 5.5% CD), lupus erythematosus (1.3% DH and 0.3% CD), Sjögren's syndrome (1.0% DH and 2.9% CD), sarcoidosis (1.3% DH and 1.8% CD), and vitiligo or alopecia areata (1.6% DH and 0% CD). We have shown that patients with DH are similar to those with CD in that many have associated endocrine or connective tissue disorders. Most of these diseases began before DH had been diagnosed suggesting that those on a gluten-free diet are not at special risk of contracting them.

HLA CLASS II REGION GENES AND SUSCEPTIBILITY TO DERMATITIS HERPETIFORMIS: DPB1 AND TAP2 ASSOCIATIONS ARE SECONDARY TO THOSE OF THE DQ SUBREGION

Classical dermatitis herpetiformis (DH) is associated with similar HLA class I, II and III polymorphisms to coeliac disease (CD). The two diseases share distinctive pathological changes to the small intestinal mucosa which reverse on withdrawal of dietary gluten. In order to determine the locus primarily associated with DH, and to examine whether there is a common genetic link predisposing to the enteropathy seen in both DH and coeliac disease, HLA-DR, DQ and DP subregion associations were investigated by HLA genotyping in 23 DH patients and 64 healthy controls. We also studied polymorphisms of the TAP2 locus, which is located between the DP and DQ subregions. Genotyping was carried out by PCR of genomic DNA with allelic assignment by sequence-specific oligonucleotide (SSO) hybridization or amplification refractory mutation system (ARMS). The strongest associations in the patient group were with HLA DRB1*0301 (91% vs 22% of controls), HLA DQB1*02 (100% vs 32% of controls) and DPB1*0101 (39% and 14%). These associations are similar to those described for CD. 100% of DH patients were positive for the DQA1*0501/DQB1*02 dimer in cis or trans and, by analogy with CD, this is probably responsible for presenting gliadin peptide implicated in the disease process. Homozygosity for DQ2 was significantly increased in the CD patient group compared to the DH patient group (65% versus 39%), and so differences in dosage of HLA class II genotypes between DH and CD may be responsible for the milder gastrointestinal symptoms characteristic of DH.

Incidence of familial dermatitis herpetiformis

Dermatitis herpetiformis (DH) and coeliac disease (CD) are gluten-sensitive diseases which have a common immunogenetic background, with the histocompatibility locus antigen (HLA) alleles DQ A1*0501 and B1*0201 in the short arm of chromosome 6. CD is well known to cluster in families whereas DH has not been generally regarded as a familial disease. To study the familial incidence of DH, a prospective study was started in 1969 at the Department of Dermatology of Helsinki University Hospital and in 1976 at the Department of Dermatology of Tampere University Hospital. A total of 1018 patients with DH were diagnosed and questioned for positive family histories. Of the 999 unrelated DH patients, 105 (10.5%) had one or several affected first-degree relatives. The disease in the relatives was either DH (4.4%) or CD (6.1%). Analysis of the 105 families showed that 13.6% of parents, 18.7% of siblings and 14.0% of children were affected, a segregation pattern which fits well to a dominant mode of Mendelian inheritance. Gender may also be important because the first-degree relatives affected with DH were more often females and those affected with CD twice as often females as males. In contrast, there were more males among the 105 propositi with DH and also among the 894 DH patients with no affected relatives. The present study clearly shows that DH is a familial disease in which the first-degree relatives can be affected both with DH and CD, presumably because of a common genetic background. The environmental factors which could cause the rather high penetrance of DH and CD in the first-degree relatives of DH patients remain unknown.

Lack of proliferative response by gluten-specific T cells in the blood and gut of patients with dermatitis herpetiformis

The majority of patients with Dermatitis Herpetiformis (DH) have a gluten-sensitive enteropathy which may be triggered by a T cell-mediated immune response to gluten. Using a proliferative assay, the responses to gluten fraction III, recall antigens and mitogens of peripheral blood mononuclear cells (PBMC) and gut T cell lines (TCL) isolated from patients with Dermatitis Herpetiformis (DH) and normal controls were studied. In most cases, neither PBMC nor gut T cell lines (which were predominantly CD3 +, CD4 +, TCR αβ +) from either controls or patients proliferated in response to gluten fraction III alone. However, the addition of 10 U/ml IL-2 to PBMC cultures containing gluten fraction III resulted in a marked increase in proliferation in 9 19 DH patients and 7 11 controls compared to IL-2 alone. Furthermore, gluten-induced upregulation of IL-2 receptor (CD25) expression was demonstrated on PBMC from 4 4 patients with DH and 2 3 controls after 7 days' culture with antigen. A similar effect by exogenous IL-2, or the same concentration of IL-4, was observed in 8 11 ( P=0.02) and 5 6 respectively DH, and 3 4 normal gut T cell lines. No difference was observed in the response of DH and control PBMC to Tetanus toxin, Candida albicans and PPD; both normal and DH gut T cell lines were unresponsive to these antigens. However, the addition of IL-2 increased the response to Candida albicans by DH gut T cell lines. Moreover, the response of DH gut T cell lines to PHA ( P<0.001), Concanavalin A and anti-CD3 were markedly reduced compared to PBMC from the same patients. These findings suggest that gluten-specific T cells present in the blood and gut of normal and DH individuals are activated by but do not proliferate in response to specific antigen.

The association between coeliac disease, dermatitis herpetiformis and certain HLA-antigens in Icelanders.

Twenty-eight cases of coeliac disease (CD) and seven of dermatitis herpetiformis (DH) have been verified in Iceland. Standard serological techniques were used for HLA typing. Twenty-five individuals with CD were typed, 21 (84%) of whom carried DR3,DQ2. Twelve of these 25 (48%) had DR3,DR7, DQ2, which makes them possibly homozygous for DQ2, and suggests that homozygosity of DQ2 increases the risk for CD. The four DH patients that were typed all had HLA-B8,DR3,DQ2. It is concluded that CD and DH are associated with DR3, DQZ in Icelanders.

Polymorphism of the tumor necrosis factor genes in patients with dermatitis herpetiformis.

In 18 patients with dermatitis herpetiformis (DH) of whom 16 were HLA-DR3 positive and 14 had the HLA-B8, -DR3 haplotype, the frequencies of known mutations of the tumor necrosis factor alpha (TNF-alpha) and TNF-beta genes were investigated using restriction fragment length polymorphism analysis and the single-strand conformational polymorphism technique. In DH, the phenotype frequency (28%) and allele frequency (0.58) of the rare TNF-beta allele TNFB*1 were significantly increased (normal control 12.4% and 0.37). For the TNF-alpha promoter/enhancer polymorphism, the rare allele TNF2 was more frequent in DH patients (11%, 0.47) compared to controls (2%, 0.16). Since functional studies have associated the rare TNFB*1 and TNF2 alleles with a higher secretion of TNF upon activation in vitro, the predominance of these two 'high-response' TNF alleles in DH patients may represent a genetic basis for the chronic inflammatory response in the skin and mucosal tissues of patients with DH.

IgA antibodies against reticulin and endomysium in the serum and gastrointestinal secretions of patients with dermatitis herpetiformis.

Although IgA is present in the skin of patients with dermatitis herpetiformis (DH), the relationship of that IgA to the mucosal immune response is not known. The purpose of this study was to determine if IgA antibodies directed against tissue antigens, which are present in the serum of patients with DH, are also present in the gut secretions of these patients. Serum and gut secretions from 8 patients with DH and 5 control subjects were analyzed by indirect immunofluorescence for the presence of IgA antireticulin and antiendomysium antibodies. IgA antibodies against reticulin (3 of 8 patients) and endomysium (4 of 8 patients) were found in the serum of patients with DH. IgA antibodies were also present in the gut secretions of all of these patients, but not in subjects (patients with DH and controls) that did not have serum IgA antireticulin or antiendomysium antibodies. The presence of IgA antireticulin and antiendomysium in both the serum and gut secretions of DH patients suggests that these antibodies arise as a result of the mucosal immune response and that IgA of mucosal origin can persist in the serum of patients with DH.

Dermatitis herpetiformis--an autoimmune disease due to cross-reaction between dietary glutenin and dermal elastin?

Dermatitis herpetiformis (DH), is associated with skin eruptions and granular depositions of IgA in the papillary dermis, but this is not a feature of coeliac disease (CD). The specificity of the IgA in the skin is unknown. High molecular weight glutenin (HMW-g), a component of gluten, has been shown to have structural similarities to human elastin. This paper reports immunoadsorption studies which suggest that human serum may contain antibodies which cross-react with HMW-g and elastin. DH patients had significantly lower levels of IgA antibodies to HMW-g and to elastin than both CD patients and healthy controls. Furthermore, introduction of a gluten-free diet (GFD) was associated with a further reduction in the amount of IgA antibodies to elastin in the DH patients. This diet-associated decrease of elastin antibodies was restricted to the IgA isotype. A significant correlation was observed between IgA antibodies to HMW-g and elastin in healthy controls and CD patients, while no such correlation was found in patients with DH. These findings could indicate that HMW-g induces production of antibodies to elastin, which are deposited in the skin, and that when the antigenic stimulus is removed, these antibodies are further reduced due to continuous dermal deposition. It is postulated that DH may be an autoimmune disease due to cross-reactivity between dietary glutenin and dermal elastin.

Adenovirus 12 and dermatitis herpetiformis.

Previous studies have shown that A-gliadin, a major gluten-derived peptide known to activate the gluten-sensitive enteropathy (GSE) of coeliac disease (CD), and the non-structural E1B peptide produced during early lytic gastrointestinal infection with human adenovirus type 12 (AD12) share an identical twelve amino acid sequence. It is suggested that immunological cross reactivity between these two peptides may play an important role in the pathogenesis of CD. As a milder but histologically identical GSE is found in the majority of patients with dermatitis herpetiformis (DH), a condition also thought to be caused by dietary gluten, we postulated that AD12 may also be involved in the pathogenesis of DH. To test this we assayed sera from 40 patients with DH and 18 healthy controls for AD12-neutralizing antibodies as evidence of past viral exposure. Detectable AD12 antibodies (titre of 13 or higher) were found in only 15% (6/40) of DH patients, compared with 27.8% (5/18) controls (not significant). These findings do not support a causative role for AD12 in the pathogenesis of DH.

Serologic Markers of Gluten-Sensitive Enteropathy in Bullous Diseases

Dermatitis herpetiformis (DH) is characterized immunologically by the presence of IgA immune deposits in the skin and by the presence of various serum antibodies. Of these, antibodies to gliadin, reticulin, and endomysium have been found to be significant. There are, however, conflicting reports as to the exact specificity and sensitivity of these serologic markers in diagnosing DH. We examined the disease specificity of these three antibody markers in 14 patients with DH, in 98 patients with pemphigus and pemphigoid, and in 26 normal subjects. Reticulin and endomysium antibodies were detected by indirect immunofluorescence and gliadin antibodies by means of the enzyme-linked immunosorbent assay method. Among the various bullous diseases, endomysial and reticulin antibodies were found to be disease specific for DH. Endomysial antibodies occurred in twice the number of DH patients (72%) compared with the occurrence of reticulin antibodies (36%). Antigliadin antibodies were detected in two thirds of DH patients and were not disease specific since increased frequencies of these antibodies were also detected in patients with pemphigus and pemphigoid. These studies support the earlier findings of the high degree of specificity of endomysial antibodies for DH and, thus, help to differentiate DH from other bullous disorders.

The use of cimetidine to reduce dapsone-dependent methaemoglobinaemia in dermatitis herpetiformis patients.

1. We have attempted to reduce dapsone-dependent methaemoglobinaemia formation in six dermatitis herpetiformis patients stabilised on dapsone by the co-administration of cimetidine. 2. In comparison with control, i.e. dapsone alone, methaemoglobinaemia due to dapsone fell by 27.3 +/- 6.7% and 26.6 +/- 5.6% the first and second weeks after commencement of cimetidine administration. The normally cyanotic appearance of the patient on the highest dose of dapsone (350 mg day-1), underwent marked improvement. 3. There was a significant increase in the trough plasma concentration of dapsone (2.8 +/- 0.8 x 10(-5)% dose ml-1) at day 21 in the presence of cimetidine compared with control (day 7, 1.9 +/- 0.6 x 10(-5)% dose ml-1, P less than 0.01). During the period of the study, dapsone-mediated control of the dermatitis herpetiformis in all six patients was unchanged. 4. Trough plasma concentrations of monoacetyl dapsone were significantly increased (P less than 0.05) at day 21 (1.9 +/- 1.0 x 10(-5)% dose ml-1) compared with day 7 (1.6 +/- 0.9 x 10(-5)% dose ml-1:control). 5. Over a 12 h period, 20.6 +/- 8.9% (day 0) of a dose of dapsone was detectable in urine as dapsone hydroxylamine. Significantly less dapsone hydroxylamine was recovered from urine at day 14 (15.0 +/- 8.4) in the presence of cimetidine, compared with day 0 (control: P less than 0.05). 6. The co-administration of cimetidine may be of value in increasing patient tolerance to dapsone, a widely used, effective, but comparatively toxic drug.

Correlation between IgA antiendomysial antibodies and subtotal villous atrophy in dermatitis herpetiformis.

Serum IgA antiendomysial antibodies (EmA) were present in 20 (64.5%) of 31 patients with dermatitis herpetiformis (DH) on a normal diet. A significant correlation was found between these antibodies and the severity of gluten-induced jejunum damage. IgA EmA were positive in 19 (86%) of the 22 DH patients with subtotal villous atrophy, in comparison with the positivity of only one (11%) of the nine DH patients with less severe intestinal involvement (partial villous atrophy or mild abnormalities). The specificity of this test for gluten-sensitive enteropathy was 100%, these antibodies being consistently negative in biopsied disease controls showing a normal jejunal mucosa. Moreover, IgA EmA proved to be useful in monitoring the response to gluten withdrawal in DH patients, as these antibodies always disappeared in all the DH cases studied after 1 year of gluten-free diet together with the regrowth of jejunal villi. The strict relationship between IgA EmA and subtotal villous atrophy is more helpful still since the enteropathy present in DH is usually symptomless and therefore difficult to suspect.

Molecular Analysis of HLA DP and DQ Genes Associated with Dermatitis Herpetiformis

HLA class II DQ and DP genes from dermatitis herpetiformis patients were amplified and analyzed using molecular probes and compared to those from celiac disease patients and to an HLA and ethnically matched control group. In dermatitis herpetiformis, as in celiac disease, the strongest association of disease was with the DQ subregion alleles DQB1*0201 and DQA1*0501 that are linked to the DRB1*0301 allele. DQB1*0201 determines the DQw2 serologic marker whereas DRB1*0301 determines the DRw17 serologic marker (formerly termed DR3). A DP subregion allele DPB1*0301 was increased and a constellation of DPB1 alleles that included DPB1*0202, *0901, and *1301 was decreased in dermatitis herpetiformis. DPB1*0101, an allele reported to be increased in celiac disease, was not increased in dermatitis herpetiformis. DP beta chains that lack a negatively charged amino acid residue at position 69 of the DP beta chain are significantly over-represented both in dermatitis herpetiformis and celiac disease patients with the DRw17, DQw2 haplotype, compared to healthy controls with that haplotype. These data favor a multigenic model for the contribution of HLA class II D region genes to dermatitis herpetiformis susceptibility. Further, they indicate that a specific DQ molecule, when present in combination with the product of one of several different DPB1 alleles, may contribute to susceptibility to the intestinal lesion, which is common to dermatitis herpetiformis and celiac disease.

DNA Sequence Analysis and Restriction Fragment Length Polymorphism (RFLP) Typing of the HLA-DQw2 Alleles Associated with Dermatitis Herpetiformis

Dermatitis herpetiformis (DH) is a blistering autoimmune skin disease associated with a 95-100% incidence of the HLA class II antigen HLA-DQw2. Although the precise role of this antigen in the pathogenesis of DH is unclear, one theory proposes that patients with DH possess a molecularly unique subtype of the HLA-DQw2 antigen that causes immune abnormalities eventuating in the clinical manifestations of DH. To test this hypothesis, we performed DNA sequence analysis on the highly polymorphic HLA-DQB1 and HLA-DQA1 loci of eight patients with dermatitis herpetiformis. All DQB1 alleles sequenced were identical to the previously described HLA-DQB*0201 allele from HLA-DQw2 normal subjects. In addition, DQA1 alleles sequenced were identical to those alleles previously associated with HLA-DQw2 (DQA*0201, DQA*0501). These data document that although HLA-DQw2 appears to be a necessary element in the pathogenesis of DH, the development of DH is not dependent on the presence of a unique HLA-DQw2 antigen. HLA-DQ allelic typing by restriction fragment length polymorphism analysis of PCR-amplified HLA-DQA1 and HLA-DQB1 fragments was also performed in ten patients with DH to determine the allelic distribution among both HLA-DR3 (eight patients) and non-DR3 (two patients) DH patients. At the HLA-DQ beta chain locus, all patients possessed the DQB1*0201 allele. At the HLA-DQ alpha chain locus, all HLA-DR3 patients and one non-DR3 patient displayed a pattern consistent with the DQA1*0501 allele, whereas one non-DR3 patient displayed a pattern consistent with the DQA1*0201 allele. These data document that patients with DH do not express a unique HLA-DQw2 heterodimer, that the HLA-DQw2 molecules present in patients with DH have no DNA sequence differences from those found in normal HLA-DQw2 subjects and therefore that susceptibility to DH is not due to a unique HLA-DQw2 molecule.

Malignant disease in dermatitis herpetiformis

An increased incidence of gastrointestinal malignancies, particularly lymphoma, has been documented in several studies of celiac disease (l-3). In one series of 210 patients followed up in Birmingham, England, a statistically significant increase in deaths from malignancy was observed (1). Among the patients were 13 with lymphoma and 6 with gastrointestinal carcinoma. Another study in the United Kingdom identified 259 malignancies in 235 patients with celiac disease; 133 malignancies were lymphomas and the most common site of the lesion was the small intestine (3). After the association between dermatitis herpetiformis (DH) and celiac disease was recognized, it seemed natural to look also at the occurrence of lymphoma and other malignancies in DH. Several case reports and small series were published, and in 1983 Leonard et al (4) confirmed statistically that DH patients had a risk for developing lymphoma similar to that of patients with celiac disease. Although it is now well established that linear immunoglobulin A (IgA) disease is not caused by gluten (5,6), it remains of interest that the incidence of lymphoproliferative malignancies also seems to be increased in this disease (4,7).

Familial dermatitis herpetiformis

The possibility that dermatitis herpetiformis (DH) might have a genetic background had been set forth during the past 20 years. Before that only a few familial cases were reported (1–4), and several surveys of DH patients do not mention or did not find affected relatives (5–7). When DH was linked in 1966 to celiac disease (8), a known familial disease with 10 to 20% of affected first-degree relatives (9,10), it seemed natural to carry out similar surveys on relatives of patients with DH. Marks et al (11) performed jejunal biopsies on 18 relatives and showed that 7 (40%) had findings consistent with gluten-sensitive enteropathy. Reunala et al (12) investigated the families of six DH patients and found in their relatives a similar high frequency of jejunal villous atrophy. The enteropathy was often subclinical and this seems to be one reason why celiac disease has previously escaped the diagnosis in the relatives of DH patients. At present it is well documented that both in adults and in children the clinical spectrum of celiac disease can vary from the overt gastrointestinal disease with severe malabsorption to totally asymptomatic disease (13,14). Despite the increasing knowledge among dermatologists that DH has an immunogenetic background similar to that of celiac disease (CD), it is curious that only a few reports exist on familial DH.

HLA association with dermatitis herpetiformis is accounted for by a cis or transassociated DQ heterodimer.

HLA-DR, DQ, and DP restriction fragment genotyping was undertaken in 23 dermatitis herpetiformis patients and 53 healthy control subjects. HLA-DQw2 was present in 100% of patients with dermatitis herpetiformis (23 of 23) versus 40% of control subjects (21 of 53). Significant secondary associations occurred with HLA-DR3 (91% of patients versus 28% of control subjects) and DPw1 (39% of patients versus 11% of control subjects). Dermatitis herpetiformis and coeliac disease thus share an identical HLA class II association. It is likely that HLA class II genes directly influence the immune responses leading to mucosal damage in both diseases. The strongest candidate for disease susceptibility to dermatitis herpetiformis is DQw2. The HLA molecule most likely to be involved in coeliac disease is a specific DQ alpha/DQ beta heterodimer, encoded in cis arrangement in DR3 haplotypes or in trans arrangement in a DR5, 7 genotype. Our data on dermatitis herpetiformis patients fits this model perfectly. All these patients are capable of expressing this molecule, which may be responsible for the gluten sensitive enteropathy seen in a subgroup of patients with dermatitis herpetiformis and coeliac disease.

Small intestinal function and dietary status in dermatitis herpetiformis.

Small intestinal morphology and function were assessed in 82 patients with dermatitis herpetiformis, 51 of whom were taking a normal diet and 31 a gluten free diet. Methods used were histopathological evaluation of jejunal mucosal biopsy specimens, quantitation of intraepithelial lymphocytes, cellobiose/mannitol permeability test, tissue disaccharidase values, serum antigliadin antibodies, and formal assessment of dietary gluten content by a dietician. There was no correlation between dietary gluten intake and the degree of enteropathy in the 51 patients taking a normal diet, whereas biopsy specimens were normal in 24 of the 31 patients on a gluten free diet, all previously having been abnormal. Eighteen patients on gluten containing diets had normal jejunal histology and in seven of these all tests of small intestinal morphology and function were entirely normal. Intestinal permeability was abnormal and serum antigliadin antibodies were present in most patients with enteropathy. Studies of acid secretion in seven patients showed that hypochlorhydria or achlorhydria did not lead to abnormal permeability in the absence of enteropathy. This study shows that a combination of objective tests of small intestinal architecture and function will detect abnormalities in most dermatitis herpetiformis patients, including some with histologically normal jejunal biopsy specimens. Nevertheless there is a small group in whom all conventional intestinal investigations are entirely normal.

Extracellular Binding Sites on IGA Anti-Jejunal Antibodies on Normal Small Bowel Detected by Indirect Immunoelectronmicroscopy

Patients with dermatitis herpetiformis (DH) have IgA deposition in the papillary dermis and in the lamina propria of the small bowel. In addition, most of DH patients' sera contain IgA class anti-reticulin antibodies, anti-endomysium antibodies (EMA), and anti-jejunal antibodies (JAB) during times of gluten intake. In previous studies, JAB and EMA seemed to be identical and related to the group of anti-reticulin antibodies. In the present study, pre-embedding en bloc immunoelectronmicroscopic methods were applied for analysis of the ultrastructural binding sites of JAB on monkey and rabbit small bowels. These substrates were incubated with sera from DH patients strongly positive for JAB. Simultaneous investigations with the PAP technique and with 5 nm gold-labeled protein A or second antibodies visualized the bound IgA identically: it was associated with collagen fibrils underlying the epithelial and cryptal basement membranes and with collagen fibrils around capillaries. Staining was also detected along the endomysial collagen fibrils of smooth muscle layers, around elastica and smooth muscle cells of blood vessel walls, and along collagen fibrils near smooth muscle cells in the lamina propria. Neither the peroxidase product nor gold deposition was detected directly on the fibers, but was associated with amorphous material surrounding collagen fibers of different diameters. The distribution of JAB-stained structures corresponded to the localization of reticulin network of the small bowel. Our data indicate that JAB recognize an antigen or antigens associated with an amorphous component of the reticulin-collagen structure of jejunum and may have identical binding sites, as anti-reticulin antibodies and EMA.